The cell-wall antigen from Eubacterium saburreum strain L 13, a new type of biopolymer

Structural studies of the O-antigenic polysaccharides from the enteroaggregative Escherichia coli strain 94/D4 and the international type strain Escherichia coli O82

The structure of the O-antigen polysaccharides (PS) from the enteroaggregative Escherichia coli strain 94/D4 and the international type strain E. coli O82 have been determined. Component analysis and (1)H, (13)C, and (31)P NMR spectroscopy experiments were employed to elucidate the structure. Inter-residue correlations were determined by (1)H, (13)C-heteronuclear multiple-bond correlation, and (1)H, (1)H-NOESY experiments. D-GroA as a substituent is linked via its O-2 in a phosphodiester-linkage to O-6 of the alpha-D-Glcp residue. The PS is composed of tetrasaccharide repeating units with the following structure: -->4)-alpha-D-Glcp6-(P-2-D-GroA)-(1-->4)-beta-D-Galp-(1-->4)-beta-D-Glcp-(1-->3)-beta-D-GlcpNAc-(1--> Cross-peaks of low intensity from an alpha-D-Glcp residue were present in the NMR spectra and spectral analysis indicates that they originate from the terminal residue of the polysaccharide. Consequently, the biological repeating unit has a 3-substituted N-acetyl-D-glucosamine residue at its reducing end. Enzyme immunoassay using specific anti-E. coli O82 rabbit sera showed identical reactivity to the LPS of the two strains, in agreement with the structural analysis of their O-antigen polysaccharides.

Escherichia coli serotype K45 capsular antigen: a glycan containing 3-acetamido-3,6-dideoxygalactopyranose

The primary structure of the acidic capsular antigen of Escherichia coli O8:K45:H9 was shown by glycose analysis, methylation analysis, and one- and two-dimensional 1H and 13C NMR spectroscopy to be composed of repeating branched tetrasaccharide units having the structure: [formula: see text] The polysaccharide contains the uncommon amino sugar 3-acetamido-3,6-dideoxy-D- galactopyranose, which has not been previously identified in a capsular antigen.

Structural studies of the Vibrio cholerae O:3 O-antigen polysaccharide

The structure of the Vibrio cholerae O:3 O-antigen polysaccharide has been investigated, mainly by n.m.r. spectroscopy, mass spectrometry, sugar and methylation analysis, and specific degradations, and is proposed to involve the following tetrasaccharide repeating-unit. [formula: see text]. In this structure, D-D-Hep is D-glycero-D-manno-heptose, Asc is 3,6-dideoxy-L-arabino-hexose (ascarylose), and Sug is 2,4-diamino-2,4,6-trideoxy-D-glucose (bacillosamine) in which N-2 is acetylated and N-4 is acylated with a 3,5-dihydroxyhexanoic acid. That the 2,4-diamino-2,4,6-trideoxy-D-glucose residue is linked through O-3 and not through one of the hydroxyl groups in the 3,5-dihydroxyhexanoyl group is indicated but not definitely proved. The configuration of the latter group has not been determined. The f.a.b.-mass spectrum of the methylated O-antigen indicates that the structure given above also represents the biological repeating-unit.

Structural studies of the O-specific side-chains of the Escherichia coli O2 lipopolysaccharide

The structure of the O-specific side-chains of the Escherichia coli O2 lipopolysaccharide has been investigated, different 1H- and 13C-n.m.r. techniques being the main methods used. It is concluded that they are composed of pentasaccharide repeating-units having the following structure, in which D-Fuc3NAc is 3-acetamido-3,6-dideoxy-D-galactose. ----4)-beta-D-GlcpNAc-(1----3)-alpha-L-Rhap-(1----2)-alpha-L-Rh ap-(1----3)-beta-L-Rhap-(1----2 increases 1 alpha-D-Fucp3NAc.